Treasury forecasts have been criticised for being wide of the mark this year as a promised surplus turned into a deficit exceeding 1 per cent of GDP. This chart shows the alternate realities of budget predictions going back to 2007.

The solid black line shows the actual budget outcome in each year. The dotted lines show the forward estimates from that year's budget.

Mr Swan pointed to Australia's debt levels as proof of the underlying strength of our economic position. "The hit to our tax collections will see our very low level of net debt peak at 11.4 per cent of GDP, still less than one-eighth the level of major advanced economies," he said.

This chart shows Australia's net debt compared with major economies in the region and around the world.

The Treasurer also said the impact on government revenues was at generational highs. "Let's be clear about the magnitude of the hit to revenue. This year we face the second largest revenue writedown since the Great Depression," he said.